The Therapeutic Implications of Tea Polyphenols Against Dopamine (DA) Neuron Degeneration in Parkinson's Disease (PD)

Residues of chlorpyrifos in the environment induce resistance in Aedes albopictus by affecting its olfactory system and neurotoxicity

Aedes albopictus, a virus-vector pest, is primarily controlled through the use of insecticides. In this study, we investigated the mechanisms of resistance in Ae. albopictus in terms of chlorpyrifos neurotoxicity to Ae. albopictus and its effects on the olfactory system. We assessed Ca2+-Mg2+-ATP levels, choline acetyltransferase (ChAT), Monoamine oxidase (MAO), odorant-binding proteins (OBPs), and olfactory receptor (OR7) gene expression in Ae. albopictus using various assays including Y-shaped tube experiments and DanioVision analysis to evaluate macromotor behavior. Our findings revealed that cumulative exposure to chlorpyrifos reduced the activity of neurotoxic Ca2+-Mg2+-ATPase and ChAT enzymes in Ae. albopictus to varying degrees, suppressed MAO-B enzyme expression, altered OBPs and OR7 expression patterns, as well as affected evasive response, physical mobility, and cumulative locomotor time under chlorpyrifos stress conditions for Ae. albopictus individuals. Consequently, these changes led to decreased feeding ability, reproductive capacity, and avoidance behavior towards natural enemies in Ae. albopictus populations exposed to chlorpyrifos stressors over time. To adapt to unfavorable living environments, Ae. albopictus may develop certain tolerance mechanisms against organophosphorus pesticides. This study provides valuable insights for guiding rational insecticide usage or dosage adjustments targeting the nervous system of Ae. albopictus.

Dietary flavonoids modulate the gut microbiota: A new perspective on improving autism spectrum disorder through the gut-brain axis

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with an unknown etiology. It is associated with various factors and causes great inconvenience to the patient's life. The gut-brain axis (GBA), which serves as a bidirectional information channel for exchanging information between the gut microbiota and the brain, is vital in studying many neurodegenerative diseases. Dietary flavonoids provide anti-inflammatory and antioxidant benefits, as well as regulating the structure and function of the gut microbiota. The occurrence and development of ASD are associated with dysbiosis of the gut microbiota. Modulation of gut microbiota can effectively improve the severity of ASD. This paper reviews the links between gut microbiota, flavonoids, and ASD, focusing on the mechanism of dietary flavonoids in regulating ASD through the GBA.

[Recent research on the role of oxidative stress in the pathogenesis of attention deficit hyperactivity disorder]

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder in children and adolescents, and its etiology and pathogenesis are still unclear. Brain is the organ with the largest oxygen consumption in human body and is easily affected by oxidative imbalance. Oxidative stress has become the key research direction for the pathogenesis of ADHD, but there is still a lack of relevant studies in China. Based on the latest research findings in China and overseas, this article reviews the clinical and experimental studies on oxidative stress in ADHD and explores the association of oxidative stress with neurotransmitter imbalance, neuroinflammation, and cell apoptosis in the pathogenesis of ADHD, so as to provide new research ideas for exploring the pathogenesis of ADHD.

Natural Phenolic Compounds with Neuroprotective Effects

Neurodegenerative disorders are characterized by mitochondrial dysfunction and subsequently oxidative stress, inflammation, and apoptosis that contribute to neuronal cytotoxicity and degeneration. Huntington's (HD), Alzheimer's (AD), and Parkinson's (PD) diseases are three of the major neurodegenerative diseases. To date, researchers have found various natural phytochemicals that could potentially be used to treat neurodegenerative diseases. Particularly, the application of natural phenolic compounds has gained significant traction in recent years, driven by their various biological activities and therapeutic efficacy in human health. Polyphenols, by modulating different cellular functions, play an important role in neuroprotection and can neutralize the effects of oxidative stress, inflammation, and apoptosis in animal models. This review focuses on the current state of knowledge on phenolic compounds, including phenolic acids, flavonoids, stilbenes, and coumarins, as well as their beneficial effects on human health. We further provide an overview of the therapeutic potential and mechanisms of action of natural dietary phenolics in curing neurodegenerative diseases in animal models.

Reactive oxygen species in biological systems: Pathways, associated diseases, and potential inhibitors-A review

Reactive oxygen species (ROS) are produced under normal physiological conditions and may have beneficial and harmful effects on biological systems. ROS are involved in many physiological processes such as differentiation, proliferation, necrosis, autophagy, and apoptosis by acting as signaling molecules or regulators of transcription factors. In this case, maintaining proper cellular ROS levels is known as redox homeostasis. Oxidative stress occurs because of the imbalance between the production of ROS and antioxidant defenses. Sources of ROS include the mitochondria, auto-oxidation of glucose, and enzymatic pathways such as nicotinamide adenine dinucleotide phosphate reduced (NAD[P]H) oxidase. The possible ROS pathways are NF-κB, MAPKs, PI3K-Akt, and the Keap1-Nrf2-ARE signaling pathway. This review covers the literature pertaining to the possible ROS pathways and strategies to inhibit them. Additionally, this review summarizes the literature related to finding ROS inhibitors.

Plausible Role of Mitochondrial DNA Copy Number in Neurodegeneration-a Need for Therapeutic Approach in Parkinson's Disease (PD)

Parkinson's disease (PD) is an advancing age-associated progressive brain disorder which has various diverse factors, among them mitochondrial dysfunction involves in dopaminergic (DA) degeneration. Aging causes a rise in mitochondrial abnormalities which leads to structural and functional modifications in neuronal activity and cell death in PD. This ends in deterioration of mitochondrial function, mitochondrial alterations, mitochondrial DNA copy number (mtDNA CN) and oxidative phosphorylation (OXPHOS) capacity. mtDNA levels or mtDNA CN in PD have reported that mtDNA depletion would be a predisposing factor in PD pathogenesis. To maintain the mtDNA levels, therapeutic approaches have been focused on mitochondrial biogenesis in PD. The depletion of mtDNA levels in PD can be influenced by autophagic dysregulation, apoptosis, neuroinflammation, oxidative stress, sirtuins, and calcium homeostasis. The current review describes the regulation of mtDNA levels and discusses the plausible molecular pathways in mtDNA CN depletion in PD pathogenesis. We conclude by suggesting further research on mtDNA depletion which might show a promising effect in predicting and diagnosing PD.

Therapeutic considerations of bioactive compounds in Alzheimer's disease and Parkinson's disease: Dissecting the molecular pathways

Leading neurodegenerative diseases Alzheimer's disease (AD) and Parkinson's disease (PD) are characterized by the impairment of memory and motor functions, respectively. Despite several breakthroughs, there exists a lack of disease-modifying treatment strategies for these diseases, as the available drugs provide symptomatic relief and bring along side effects. Bioactive compounds are reported to bear neuroprotective properties with minimal toxicity, however, a detailed elucidation of their modes of neuroprotection is lacking. The review elucidates the neuroprotective mechanism(s) of some of the major phyto-compounds in pre-clinical and clinical studies of AD and PD to understand their potential in combating these diseases. Curcumin, eugenol, resveratrol, baicalein, sesamol and so on have proved efficient in countering the pathological hallmarks of AD and PD. Curcumin, resveratrol, caffeine and so on have reached the clinical phases of these diseases, while aromadendrin, delphinidin, cyanidin and xanthohumol are yet to be extensively explored in pre-clinical phases. The review highlights the need for extensive investigation of these compounds in the clinical stages of these diseases so as to utilize their disease-modifying abilities in the real field of treatment. Moreover, poor pharmacokinetic properties of natural compounds are constraints to their therapeutic yields and this review suggests a plausible contribution of nanotechnology in overcoming these limitations.

Polyphenols in Inner Ear Neurobiology, Health and Disease: From Bench to Clinics

There is substantial experimental and clinical interest in providing effective ways to both prevent and slow the onset of hearing loss. Auditory hair cells, which occur along the basilar membrane of the cochlea, often lose functionality due to age-related biological alterations, as well as from exposure to high decibel sounds affecting a diminished/damaged auditory sensitivity. Hearing loss is also seen to take place due to neuronal degeneration before or following hair cell destruction/loss. A strategy is necessary to protect hair cells and XIII cranial/auditory nerve cells prior to injury and throughout aging. Within this context, it was proposed that cochlea neural stem cells may be protected from such aging and environmental/noise insults via the ingestion of protective dietary supplements. Of particular importance is that these studies typically display a hormetic-like biphasic dose-response pattern that prevents the occurrence of auditory cell damage induced by various model chemical toxins, such as cisplatin. Likewise, the hormetic dose-response also enhances the occurrence of cochlear neural cell viability, proliferation, and differentiation. These findings are particularly important since they confirmed a strong dose dependency of the significant beneficial effects (which is biphasic), whilst having a low-dose beneficial response, whereas extensive exposures may become ineffective and/or potentially harmful. According to hormesis, phytochemicals including polyphenols exhibit biphasic dose-response effects activating low-dose antioxidant signaling pathways, resulting in the upregulation of vitagenes, a group of genes involved in preserving cellular homeostasis during stressful conditions. Modulation of the vitagene network through polyphenols increases cellular resilience mechanisms, thus impacting neurological disorder pathophysiology. Here, we aimed to explore polyphenols targeting the NF-E2-related factor 2 (Nrf2) pathway to neuroprotective and therapeutic strategies that can potentially reduce oxidative stress and inflammation, thus preventing auditory hair cell and XIII cranial/auditory nerve cell degeneration. Furthermore, we explored techniques to enhance their bioavailability and efficacy.

Neuroprotective effect of chlorogenic acid on Parkinson's disease like symptoms through boosting the autophagy in zebrafish

Parkinson's disease (PD) is characterized by both motor and non-motor symptoms, including hypokinesia, postural instability, dopaminergic (DA) neurons loss, and α-synuclein (α-syn) accumulation. A growing number of patients show negative responses towards the current therapies. Thus, preventative or disease-modifying treatment agents are worth to further research. In recent years, compounds extracted from natural sources become promising candidates to treat PD. Chlorogenic acid (CGA) is a phenolic compound appearing in coffee, honeysuckle, and eucommia that showed their potential as antioxidants and neuroprotectors. In this study, we investigated the anti-PD activity of CGA by testing its effect on 1-methyl-4-phenyl-1-1,2,3,6-tetrahydropyridine (MPTP) zebrafish model of PD. It was shown that CGA relieved MPTP-induced PD-like symptoms including DA neurons and blood vessel loss, locomotion reduction, and apoptosis events in brain. Moreover, CGA modulated the expression of PD- and autophagy-related genes (α-syn, lc3b, p62, atg5, atg7, and ulk1b), showing its ability to promote the autophagy which was interrupted in the PD pathology. The unblocked effect of CGA on autophagy was further verified in 6-hydroxydopamine (6-OHDA)-modeled SHSY5Y cells. Our findings indicated that CGA might relieve PD by boosting the autophagy in neuronal cells that makes CGA a potential candidate for anti-PD treatment.

Role of dopamine in the pathophysiology of Parkinson's disease

A pathological feature of Parkinson's disease (PD) is the progressive loss of dopaminergic neurons and decreased dopamine (DA) content in the substantia nigra pars compacta in PD brains. DA is the neurotransmitter of dopaminergic neurons. Accumulating evidence suggests that DA interacts with environmental and genetic factors to contribute to PD pathophysiology. Disturbances of DA synthesis, storage, transportation and metabolism have been shown to promote neurodegeneration of dopaminergic neurons in various PD models. DA is unstable and can undergo oxidation and metabolism to produce multiple reactive and toxic by-products, including reactive oxygen species, DA quinones, and 3,4-dihydroxyphenylacetaldehyde. Here we summarize and highlight recent discoveries on DA-linked pathophysiologic pathways, and discuss the potential protective and therapeutic strategies to mitigate the complications associated with DA.

Mitochondrial dysfunction-targeting therapeutics of natural products in Parkinson's disease

Parkinson's disease (PD), the second most common neurodegenerative disease worldwide, often occurs in middle-aged and elderly individuals. The pathogenesis of PD is complex and includes mitochondrial dysfunction, and oxidative stress. Recently, natural products with multiple structures and their bioactive components have become one of the most important resources for small molecule PD drug research targeting mitochondrial dysfunction. Multiple lines of studies have proven that natural products display ameliorative benefits in PD treatment by regulating mitochondrial dysfunction. Therefore, a comprehensive search of recent published articles between 2012 and 2022 in PubMed, Web of Science, Elesvier, Wliey and Springer was carried out, focusing on original publications related to natural products against PD by restoring mitochondrial dysfunction. This paper presented the mechanisms of various kinds of natural products on PD-related mitochondrial dysfunction regulation and provided evidence that natural products are promising to be developed as drugs for PD therapeutics.

Antioxidant effects of silver nanoparticles obtained by green synthesis from the aqueous extract of Eryngium carlinae on the brain mitochondria of streptozotocin-induced diabetic rats

Diabetes mellitus is a metabolic disorder characterized by chronic hyperglycemia that affects practically all tissues and organs, being the brain one of most susceptible, due to overproduction of reactive oxygen species induced by diabetes. Eryngium carlinae is a plant used in traditional Mexican medicine to treat diabetes, which has already been experimentally shown have hypoglycemic, antioxidant and hypolipidemic properties. The green synthesis of nanoparticles is a technique that combines plant extracts with metallic nanoparticles, so that the nanoparticles reduce the absorption and distribution time of drugs or compounds, increasing their effectiveness. In this work, the antioxidant effects and mitochondrial function in the brain were evaluated, as well as the hypoglycemic and hypolipidemic effect in serum of both the aqueous extract of the aerial part of E. carlinae, as well as its combination with silver nanoparticles of green synthesis. Administration with both, extract and the combination significantly decreased the production of reactive oxygen species, lipid peroxidation, and restored the activity of superoxide dismutase 2, glutathione peroxidase, and electron transport chain complexes in brain, while that the extract-nanoparticle combination decreased blood glucose and triglyceride levels. The results obtained suggest that both treatments have oxidative activity and restore mitochondrial function in the brain of diabetic rats.

Discovery of novel 2-hydroxyl-4-benzyloxybenzyl aniline derivatives as potential multifunctional agents for the treatment of Parkinson's disease

To discover novel multifunctional agents for the treatment of Parkinson's disease, a series of 2-hydroxyl-4-benzyloxybenzyl aniline derivatives was designed, synthesized and evaluated. The biological screening indicated that representative compound 6h possessed excellent MAO-B inhibition (IC₅₀ = 0.014 μM), high antioxidant activity (ORAC = 2.14 Trolox equivalent), good metal chelating ability, appropriate BBB permeability and significant neuroprotective effect. Additionally, 6h exhibited great ability to alleviate the neuroinflammtion by suppressing the activation of NF-κB pathway in vitro. Furthermore, 6h can also ameliorate MPTP induced Parkinson's disease symptoms in mice by improving the dopamine level and repressing oxidative damage. These results indicated that compound 6h was a promising candidate for further development against PD.

A novel micropattern platform constructed by TiO2 oxidation of PDA

Dopamine is a small molecule inspired by the dopamine motif of mussel foot proteins, and PDA is formed by the self-polymerization of dopamine. Under the UV-irradiation，PDA would be oxidized by reactive oxygen species (ROS) which were produced by photocatalytic reactions on TiO₂ surfaces，thus regulating the adhesion behavior of endothelial cells (ECs) TiO₂ inhibited platelet (Plt) adhesion after UV exposure. Polydopamine (PDA)-TiO₂ micropatterns (P-PDA-TiO₂) were prepared by magnetron sputtering and photolithography. This micropatterns successfully achieves selective adhesion of Plt and ECs. The selective adhesion of ECs disappears after vacuum reduction. In contrast to conventional cell patterning strategies, P-PDA-TiO₂ can easily achieve pattern separation of ECs and Plts and provide a new concept for building complex blood-contacting devices.

Dietary and Environmental Risk Factors in Parkinson's and Alzheimer's Disease: A Semi-Quantitative Pilot Study

Objective

Environmental influence and dietary variations are well-known risk factors for various diseases including neurodegenerative disorders. Preliminary evidence suggests that diet in early-life and living environment might influence the incidence of Parkinson's disease (PD) in later phase of life. There have been limited epidemiologic studies on this aspect especially in India. In this hospital-based case-control study, we intended to identify dietary and environmental risk factors of PD.

Methods

Patients with PD (n = 105), Alzheimer's disease (AD) (n = 53) and healthy individuals (n = 81) were recruited. Dietary intake and environmental exposures were assessed using a validated Food-Frequency and Environmental Hazard Questionnaire. Their demographic details and living environment were also recorded using the same questionnaire.

Results

Pre-morbid consumption of carbohydrate and fat was significantly higher whereas dietary fiber and fruit content was significantly lesser in PD as compared to AD and healthy age-matched controls. Meat and milk intake was the highest among all the food groups in PD patients. Rural living and their habitation near water bodies were significantly more frequent in PD patients.

Conclusion

We found that past intake of carbohydrate, fat, milk, and meat are associated with increased risk of PD. On the other hand, rural living and habitat near water bodies might be associated with incidence and severity of PD. Hence, preventive strategies related to dietary and environmental modulators in PD might be clinically useful in the future.

Natural Products as Modulators of Nrf2 Signaling Pathway in Neuroprotection

Neurodegenerative diseases (NDs) affect the West due to the increase in life expectancy. Nervous cells accumulate oxidative damage, which is one of the factors that triggers and accelerates neurodegeneration. However, cells have mechanisms that scavenge reactive oxygen species (ROS) and alleviate oxidative stress (OS). Many of these endogenous antioxidant systems are regulated at the gene expression level by the transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2). In the presence of prooxidant conditions, Nrf2 translocates to the nucleus and induces the transcription of genes containing ARE (antioxidant response element). In recent years, there has been an increase in the study of the Nrf2 pathway and the natural products that positively regulate it to reduce oxidative damage to the nervous system, both in in vitro models with neurons and microglia subjected to stress factors and in vivo models using mainly murine models. Quercetin, curcumin, anthocyanins, tea polyphenols, and other less studied phenolic compounds such as kaempferol, hesperetin, and icariin can also modulate Nrf2 by regulating several Nrf2 upstream activators. Another group of phytochemical compounds that upregulate this pathway are terpenoids, including monoterpenes (aucubin, catapol), diterpenes (ginkgolides), triterpenes (ginsenosides), and carotenoids (astaxanthin, lycopene). This review aims to update the knowledge on the influence of secondary metabolites of health interest on the activation of the Nrf2 pathway and their potential as treatments for NDs.

Cannabidivarin alleviates α-synuclein aggregation via DAF-16 in Caenorhabditis elegans

Cannabidivarin (CBDV), a structural analog of cannabidiol (CBD), has received attention in recent years owing to its anticonvulsant property and potential for treating autism spectrum disorder. However, the function and mechanism of CBDV involved in the progression of Parkinson's disease (PD) remain unclear. In this work, we found that CBDV inhibited α-synuclein (α-syn) aggregation in an established transgenetic Caenorhabditis elegans (C. elegans). The phenolic hydroxyl groups of CBDV are critical for scavenging reactive oxygen species (ROS), reducing the in vivo aggregation of α-syn and preventing DAergic neurons from 6-hydroxydopamine (6-OHDA)-induced injury and degeneration. By combining multiple biophysical approaches, including nuclear magnetic resonance spectrometry, transmission electron microscopy and fibrillation kinetics assays, we confirmed that CBDV does not directly interact with α-syn or inhibit the formation of α-syn fibrils in vitro. Further cellular signaling investigation showed that the ability of CBDV to prevent oxidative stress, the accumulation of α-syn and the degeneration of DAergic neurons was mediated by DAF-16 in the worms. This study demonstrates that CBDV alleviates the aggregation of α-syn in vivo and reveals that the phenolic hydroxyl groups of CBDV are critical for this activity, providing a potential for the development of CBDV as a drug candidate for PD therapeutics.

Dietary flavonoids: a novel strategy for the amelioration of cognitive impairment through intestinal microbiota

The chances of people suffering from cognitive impairments increase gradually with age. Diet and lifestyle are closely related to the occurrence and development of cognitive function. Dietary flavonoid supplementation has been shown to be one of the protective factors against cognitive decline. Flavonoids belong to a class of polyphenols that have been proposed for the treatment of cognitive decline. Recent evidence has shown that intestinal flora in the human body can interact with flavonoids. Intestinal microbiota can modify the chemical structure of flavonoids, producing new metabolites, the pharmacological activities of which may be different from those of the parent; meanwhile, flavonoids and their metabolites can, in turn, regulate the composition and structure of intestinal flora. Notably, intestinal flora affect host nervous system activity through the gut-brain axis, ultimately causing changes in cognitive function. This review therefore summarizes the interaction of dietary flavonoids and intestinal flora, and their protective effect against cognitive decline through the gut-brain axis, indicating that dietary flavonoids may ameliorate cognitive impairment through their interaction with intestinal microbiota. © 2022 Society of Chemical Industry.

Vitamin B12 Ameliorates the Pathological Phenotypes of Multiple Parkinson's Disease Models by Alleviating Oxidative Stress

Parkinson's disease (PD) is the second most common neurodegenerative disease characterized by progressive loss of dopaminergic neurons in the substantia nigra of the midbrain. The etiology of PD has yet to be elucidated, and the disease remains incurable. Increasing evidence suggests that oxidative stress is the key causative factor of PD. Due to their capacity to alleviate oxidative stress, antioxidants hold great potential for the treatment of PD. Vitamins are essential organic substances for maintaining the life of organisms. Vitamin deficiency is implicated in the pathogenesis of various diseases, such as PD. In the present study, we investigated whether administration of vitamin B12 (VB12) could ameliorate PD phenotypes in vitro and in vivo. Our results showed that VB12 significantly reduced the generation of reactive oxygen species (ROS) in the rotenone-induced SH-SY5Y cellular PD model. In a Parkin gene knockout C. elegans PD model, VB12 mitigated motor dysfunction. Moreover, in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse PD model, VB12 also displayed protective effects, including the rescue of mitochondrial function, dopaminergic neuron loss, and movement disorder. In summary, our results suggest that vitamin supplementation may be a novel method for the intervention of PD, which is safer and more feasible than chemical drug treatment.

A comprehensive review of nano-delivery system for tea polyphenols: Construction, applications, and challenges

Tea polyphenols (TPs) are important bioactive compounds in tea and have excellent physiological regulation functions. However, the extraction and purification of TPs are key technologies affecting their further application, and the chemical instability, poor bioavailability of TPs are major challenges for researchers. In the past decade, therefore, research and development of advanced carrier systems for the delivery of TPs has been greatly promoted to improve their poor stability and poor bioavailability. In this review, the properties and function of TPs are introduced, and the recent advances in the extraction and purification technologies are systematically summarized. Particularly, the intelligent delivery of TPs via novel nano-carriers is critically reviewed, and the application of TPs nano-delivery system in medical field and food industry is also described. Finally, the main limitations, current challenges and future perspectives are highlighted in order to provide research ideas for exploiting nano-delivery carriers and their application in TPs.

Study of the Effects of Nicotine and Caffeine for the Treatment of Parkinson's Disease

Parkinson's disease (PD) is considered to be a highly severe neurological disorder. PD occurs due to a decrease in dopamine production by the degeneration of dopamine-secreting neurons. Genetic mutations, environmental toxins and lifestyle are some of the risk factors of the progressive neurodegenerative disorder PD. Parkin protein, which is encoded by the PARK gene, is one of the important proteins, which is one of the causative agents. The Parkin protein has several mutations which lead to the development of the disease. Apart from PD, the mutations in Parkin also showed to be responsible for the onset of diseases like cancers. It is reported that the E28K mutation in the Ubl domain of parkin is highly deleterious and responsible for the onset of melanoma. This necessitates the development of new therapeutics against PD. Molecules like levodopa, carbidopa, monoamine oxidase type B inhibitors (MBO inhibitors), dopamine agonists, anticholinergics and amantadine are some commonly used drugs used to treat PD. Recently, there have been increasing evidence which shows that cigarette smoking and consumptions of coffee and tea could have important roles in modulating the risk of PD. Therefore, we planned to analyse the molecular mechanism of the binding interactions of nicotine, caffeine and the polyphenol ( -)-epigallocatechin-3-gallate (EGCG) from green tea with Parkin protein to predict their therapeutic potentials in PD targeting the E28K mutation. We focused on E28K mutant of Parkin as this mutant form of parkin has been shown to be the most pathogenic one. We could identify the potential therapeutic aspects of these natural products to prevent the onset of PD. This work may therefore be considered to be the first of its kind which would take into consideration the environmental toxicological approach in designing natural product inhibitors against the onset of PD.

Perspective: Is a Closer Interaction between Experimental and Clinical Research Paradigms in Chronic Neurodegeneration, Such as Parkinson's Disease, Necessary Again?

This editorial discusses the current standstill in research in Parkinson's disease from a clinician's point of view [...].

Network pharmacology-based analysis and experimental in vitro validation on the mechanism of Paeonia lactiflora Pall. in the treatment for type I allergy

Background

The incidence of allergic reaction is increasing year by year, but the specific mechanism is still unclear. Paeonia lactiflora Pall.(PLP) is a traditional Chinese medicine with various pharmacological effects such as anti-tumor, anti-inflammatory, and immune regulation. Previous studies have shown that PLP has potential anti-allergic activity. However, there is still no comprehensive analysis of the targeted effects and exact molecular mechanisms of the anti-allergic components of PLP. This study aimed to reveal the mechanism of PLP. in the treatment of type I allergy by combining network pharmacological methods and experimental verification.

Methods

First, we used the traditional Chinese medicine systems pharmacology (TCMSP) database and analysis platform to screen the main components and targets of PLP, and then used databases such as GeneCards to retrieve target information related to ‘allergy’. Protein–protein interaction (PPI) analysis obtained the core target genes in the intersection target, and then imported the intersection target into the David database for gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analysis. Furthermore, the therapeutic effect of paeoniflorin, the main component of PLP, on IgE-induced type I allergy was evaluated in vitro.

Results

GO analysis obtained the main biological processes, cell components and molecular functions involved in the target genes. KEGG analysis screened out MAPK1, MAPK10, MAPK14 and TNF that have a strong correlation with PLP anti-type I allergy, and showed that PLP may pass through signal pathways such as IgE/FcεR I, PI3K/Akt and MAPK to regulate type I allergy. RT-qPCR and Western Blot results confirmed that paeoniflorin can inhibit the expression of key genes and down-regulate the phosphorylation level of proteins in these signal pathways. It further proved the reliability of the results of network pharmacology research.

Conclusion

The results of this study will provide a basis for revealing the multi-dimensional regulatory mechanism of PLP for the treatment of type I allergy and the development of new drugs.

Network pharmacology-based analysis of the mechanism of Saposhnikovia divaricata for the treatment of type I allergy

CONTEXT

Saposhnikovia divaricata (Turcz.) Schischk (Apiaceae) (SD) has various pharmacological activities, but its effects on type I allergy (TIA) have not been comprehensively studied.

OBJECTIVE

This study evaluates the treatment and molecular mechanisms of SD against TIA.

MATERIALS AND METHODS

The effective components and action targets of SD were screened using TCMSP database, and allergy-related targets of SD were predicted using GeneCards and OMIM database. The obtained target intersections were imported into David database for GO analysis, and used R software to perform KEGG analysis. The RBL-2H3 cells sensitised by DNP-IgE/DNP-BSA were treated with different concentrations of SD (root decoction, 0.5, 1, and 2 mg/mL), prim-O-glucosylcimifugin (POG, 10, 40, and 80 μg/mL) and the positive control drug-ketotifen fumarate (KF, 30 μM) for 12 h, then subjected to cell degranulation and qPCR analysis.

RESULTS

Eighteen active compounds of SD and 38 intersection targets were obtained: TIA-related signal pathways mainly include calcium signal pathway, PI3K-Akt signal pathway and MAPK signal pathway. Taking the β-Hex release rate of the model group as the base, the release rate of SD and POG in high dose groups were 43.79% and 57.01%, respectively, which were significantly lower than model group (p < 0.01), and significantly lower than KF group (63.83%, p < 0.01, p < 0.05). SD and POG could down-regulate the expression of related proteins in the Lyn/Syk, PI3K/AKT and MAPK signalling pathways.

DISCUSSION AND CONCLUSION

Saposhnikovia divaricata could inhibit IgE-induced degranulation of mast cells, providing a scientific basis for further research and clinical applications of SD in TIA treatment.

Tea-polyphenol green fabricating catkin-like CuAg for electrochemical H2O2 detection

Green fabrication of unique structural nanoparticles has always been of increasing interest in many fields. Herein, a facile and green strategy of fabricating catkin-like CuAg nanocomposites using tea-polyphenols as reduction agent is reported. As-prepared nanocomposites have been characterized by a series of analysis. Physical characterizations show the synthesised of nanocomposites whose catkin-like special morphology. The electrochemical detection hydrogen peroxide (H2O2) results show that, catkin-like CuAg nanocomposites have good sensitivity, stability and anti-interference and it could detect without any additional mediator or enzyme. Specifically, it shows good H2O2 sensitivity of 2.55 μA mM-1cm-2 with range of 0.1-120 mM. Therefore, the catkin-like CuAg nanocomposites prepared by an environmental-friendly synthetic strategy, would provide a good reference for other green syntheses in the future.

Neurodegenerative Diseases: Can Caffeine Be a Powerful Ally to Weaken Neuroinflammation?

In recent years, there has been considerable research showing that coffee consumption seems to be beneficial to human health, as it contains a mixture of different bioactive compounds such as chlorogenic acids, caffeic acid, alkaloids, diterpenes and polyphenols. Neurodegenerative diseases (NDs) are debilitating, and non-curable diseases associated with impaired central, peripheral and muscle nervous systems. Several studies demonstrate that neuroinflammation mediated by glial cells—such as microglia and astrocytes—is a critical factor contributing to neurodegeneration that causes the dysfunction of brain homeostasis, resulting in a progressive loss of structure, function, and number of neuronal cells. This happens over time and leads to brain damage and physical impairment. The most known chronic NDs are represented by Alzheimer’s disease (AD), Parkinson’s disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and Huntington’s disease (HD). According to epidemiological studies, regular coffee consumption is associated with a lower risk of neurodegenerative diseases. In this review, we summarize the latest research about the potential effects of caffeine in neurodegenerative disorders prevention and discuss the role of controlled caffeine delivery systems in maintaining high plasma caffeine concentrations for an extended time.

Disturbance of neurotransmitter metabolism in drug-naïve, first-episode major depressive disorder: a comparative study on adult and adolescent cohorts

Neurotransmitter metabolism plays a critical role in the pathophysiology of major depressive disorder (MDD). However, whether the neurotransmitter metabolism in adolescent MDD is differentiated from adult MDD is still elusive. In the current study, plasma concentrations of monoamine and amino acid neurotransmitters as well as their metabolites, including tryptophan (TRP), kynurenine (KYN), kynurenic acid (KYNA), serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), norepinephrine (NE), vanillylmandelic acid (VMA), 3-methoxy-4-hydroxyphenylglycol (MHPG), glutamine (GLN), glutamate (GLU) and gamma-aminobutyric acid (GABA), were measured and compared in two cohorts of subjects (adult cohort: 31 first-episode MDD vs. 35 healthy controls; adolescent cohort: 33 first-episode MDD vs. 30 healthy controls). To assess the effects of antidepressant treatment, we also analyzed the concentrations of these indexes pre- and post-treatment in adult and adolescent cohorts. At baseline, the deficits of neurotransmitter metabolism in adult MDD were manifested in all the neurotransmitter systems. In contrast, for adolescent MDD, the dysregulation of neurotransmission was mainly indicated in the catecholaminergic systems. After antidepressant treatment, adult MDD showed increased TRP, KYN, KYNA and GLU levels, together with decreased levels of 5-HIAA and DOPAC. Adolescent MDD illustrated an increased level of 5-HT and decreased levels of TRP and GABA. The improvements of Hamilton total scores correlated with the changes in plasma TRP and the turnover of KYN/TRP after treatment in all MDD patients. However, these correlations were only manifested in the adult MDD rather than in adolescent MDD patients. The findings highlight the shared and distinguished neurotransmitter pathways in MDD and emphasize the different antidepressant responses between adults and adolescents. Potentially, the neurotransmitters above could serve as diagnostic biomarkers and provide a novel pharmacological treatment strategy for MDD.

Effects of artificial honey and epigallocatechin-3-gallate on streptococcus pyogenes

Background

Streptococcus pyogenes is an important global human pathogen that causes pharyngitis, and antibacterial therapy has become an important part of the overall therapy for pharyngitis. As natural derivatives, honey and green tea are often recommended for patients with pharyngitis in traditional Chinese medicine without experimental theoretical basis on wether the combined effect of honey and green tea on pharyngitis is better than they alone. The aims of this study were to explore the effects of artificial honey (AH) and epigallocatechin-3-gallate (EGCG) on S. pyogenes and elucidate the possible mechanisms, which were investigated using MIC (the minimum inhibitory concentration), FIC (fractional inhibitory concentration) index, growth pattern, biofilm formation and RT-qPCR.

Results

The MIC of AH on S. pyogenes was 12.5% (v/v) and the MIC of EGCG was 1250 μg/ml. The FIC index of AH and EGCG was 0.5. The planktonic cell growth, growth pattern and biofilm formation assays showed that AH and EGCG mixture had stronger inhibitory effect on S. pyogenes than they alone. RT-qPCR confirmed that the expression of hasA and luxS gene were inhibited by AH and EGCG mixture.

Conclusions

AH and EGCG mixture can inhibit the planktonic cell growth, biofilm formation and some virulence genes expression of S. pyogenes, better than they alone. The combination of honey and green tea have the potential to treat pharyngitis as natural derivatives, avoiding drug resistance and double infection.

Update to the Treatment of Parkinson's Disease Based on the Gut-Brain Axis Mechanism

Gastrointestinal (GI) symptoms represented by constipation were significant non-motor symptoms of Parkinson’s disease (PD) and were considered early manifestations and aggravating factors of the disease. This paper reviewed the research progress of the mechanism of the gut-brain axis (GBA) in PD and discussed the roles of α-synuclein, gut microbiota, immune inflammation, neuroendocrine, mitochondrial autophagy, and environmental toxins in the mechanism of the GBA in PD. Treatment of PD based on the GBA theory has also been discussed, including (1) dietary therapy, such as probiotics, vitamin therapy, Mediterranean diet, and low-calorie diet, (2) exercise therapy, (3) drug therapy, including antibiotics; GI peptides; GI motility agents, and (4) fecal flora transplantation can improve the flora. (5) Vagotomy and appendectomy were associated but not recommended.

Habitual tea consumption and postoperative delirium after total hip/knee arthroplasty in elderly patients: The PNDABLE study

PURPOSE

To clarify the effects of habitual tea consumption on postoperative delirium (POD) in elderly patients undergoing total hip/knee arthroplasty.

PATIENTS AND METHODS

A prospective cohort study was carried out at Qingdao Municipal Hospital Affiliated to Qingdao University between June 2020 and June 2021. A total of 332 patients aged 65-85 years undergoing total hip/knee arthroplasty under combined spinal and epidural anesthesia were enrolled from the Perioperative Neurocognitive Disorder and Biomarker Lifestyle (PNDABLE) study in the final analysis, consisting of 168 patients with habitual tea consumption and 164 patients with infrequent tea consumption. The primary endpoint was the effects of habitual tea consumption on POD and the incidence of POD, which was assessed by the Confusion Assessment Method (CAM) twice daily during the first 7 postoperative days, and POD severity was measured by the Memorial Delirium Assessment Scale (MDAS). The secondary endpoints were the concentrations of caffeine and tea polyphenols in plasma and cerebrospinal fluid (CSF), which were detected by the enzyme-linked immunosorbent assay.

RESULTS

POD occurred in 61 of 332 patients (18.37%), among whom 19 had habitual tea consumption (5.72%) and 42 had infrequent tea consumption (12.65%). Habitual tea consumption (odds ratio [OR] = 0.370, 95% confidence interval [CI]: 0.205-0.670, P = .001) was significantly associated with POD in the logistic analysis, and then after adjusting for age and American Society of Anesthesiologists (ASA) physical status (OR = 0.353, 95% CI: 0.190-0.655, P = .001). Furthermore, caffeine in T₀ plasma (OR = 0.834, 95% CI: 0.752-0.924, P = .001), T₁ plasma (OR = 0.818, 95% CI: 0.738-0.908, P < .001), and CSF (OR = 0.899, 95% CI: 0.820-0.984, P = .022) and tea polyphenols in T₀ plasma (OR = 0.541, 95% CI: 0.416-0.704, P < .001), T₁ plasma (OR = 0.477, 95% CI: 0.359-0.633, P < .001), and CSF (OR = 0.526, 95% CI: 0.397-0.696, P < .001) were associated with POD after adjusting for age and ASA physical status.

CONCLUSION

Habitual tea consumption may be associated with a lower incidence of POD in elderly patients.

Dopamine Homeostasis Imbalance and Dopamine Receptors-Mediated AC/cAMP/PKA Pathway Activation are Involved in Aconitine-Induced Neurological Impairment in Zebrafish and SH-SY5Y Cells

Aconitine is one of the main bioactive and toxic ingredients of Aconitum species. Increasingly, aconitine has been reported to induce neurotoxicity. However, whether aconitine has effects on the dopaminergic nervous system remains unclear. In this study, zebrafish embryos at 6-days postfertilization were exposed to aconitine at doses of 0.5, 1, and 2 μM for 24 h, and SH-SY5Y cells were treated with 50, 100, and 200 μM of aconitine for 24 h. Results demonstrated that aconitine treatment induced deformities and enhanced the swimming behavior of zebrafish larvaes. Aconitine exposure suppressed cell proliferation and increased the number of reactive oxygen species and apoptosis in zebrafish larvaes and SH-SY5Y cells. Aconitine altered the levels of dopamine and its metabolites by regulating the expression of genes and proteins related to dopamine synthesis, storage, degradation, and reuptake in vivo and in vitro. Moreover, aconitine activated the AC/cAMP/PKA pathway by activating the dopamine D1 receptor (D1R) and inhibiting the dopamine D2 receptor (D2R) to disturb intracellular calcium homeostasis, eventually leading to the damage of nerve cells. Furthermore, the D1R antagonist SCH23390 and D2R agonist sumanirole pretreatment effectively attenuated the excitatory state of larvaes. Sumanirole and PKA antagonist H-89 pretreatment effectively decreased intracellular Ca²⁺ accumulation induced by aconitine in vivo. SCH23390 and sumanirole also reduced aconitine-induced cytotoxicity by inhibiting the AC/cAMP/PKA pathway in vitro. These results suggested that dopamine homeostasis imbalance and dopamine receptors (DRs)-mediated AC/cAMP/PKA pathway activation might be vital mechanisms underlying aconitine-induced neurological injury.

Cannabidiol protects against Alzheimer's disease in C. elegans via ROS scavenging activity of its phenolic hydroxyl groups

Recent discoveries have implicated the potential of Cannabidiol (CBD) in the prevention of Alzheimer's disease (AD). However, how CBD affects such neurodegenerative disorders remains unclear. Herein, Caenorhabditis elegans (C. elegans) was used as the model organism to elucidate the mechanism by which CBD ameliorates AD in vivo. CBD was found to alleviate the progression of Aβ-induced AD but not tau protein-induced AD or α-syn-induced Parkinson's disease. CBD inhibited the aggregation of Aβ in C. elegans. However, CBD failed to prevent the formation of β-sheet aggregation in vitro. Moreover, CBD was found to scavenge reactive oxygen species (ROS) in vivo without inducing the overexpression of antioxidative genes. In addition, CBD treatment enhanced the worm resistance to oxidative stress, which was independent of the classical transcription factors DAF-16 and SKN-1. These results supported that the in vivo antioxidative activity of CBD was most likely due to its intrinsic antioxidative property. Furthermore, the phenolic hydroxyl groups of CBD were found to be critical for scavenging ROS in vitro and in vivo, alleviating the aggregation of Aβ in vivo, and ameliorating Aβ-associated neurotoxicity. These studies show that CBD protects against AD in C. elegans via the ROS scavenging activity of its phenolic hydroxyl groups, which provides insight for further structure-activity relationship studies of CBD as an AD therapeutic.

Parkinson's Disease: Is there a Role for Dietary and Herbal Supplements?

Parkinson's Disease (PD) is characterised by degeneration of the neurons of the nigrostriatal dopaminergic pathway of the brain. The pharmacological cornerstone of PD management is mainly the use of dopamine precursors, dopamine receptor agonists, and agents that inhibit the biochemical degradation of dopamine. While these drugs initially provide relief to the symptoms and improve the quality of life of the patients, progression of the underlying pathological processes, such as oxidative stress and neuroinflammation (which have been strongly associated with PD and other neurodegenerative disorders), eventually reduce their benefits, making further benefits achievable, only at high doses due to which the magnitude and frequency of side-effects are amplified. Also, while it is becoming obvious that mainstream pharmacological agents may not always provide the much-needed answer, the question remains what succour can nature provide through dietary supplements, nutraceuticals and herbal remedies? This narrative review examines current literature for evidence of the possible roles (if any) of nutraceuticals, dietary supplements and herbal remedies in the prevention or management of PD by examining how these compounds could modulate key factors and pathways that are crucial to the pathogenesis and/or progression of PD. The likely limitations of this approach and its possible future roles in PD prevention and management are also considered.

Neurotransmitter and Intestinal Interactions: Focus on the Microbiota-Gut-Brain Axis in Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder of unknown etiology. IBS is caused by a disruption in the gut-brain axis. Given the importance of the gut microbiota in maintaining local and systemic homeostasis of immunity, endocrine, and other physiological processes, the microbiota-gut-brain axis has been proposed as a key regulator in IBS. Neurotransmitters have been shown to affect blood flow regulation, intestinal motility, nutrient absorption, the gastrointestinal immune system, and the microbiota in recent studies. It has the potential role to play a function in the pathophysiology of the gastrointestinal and neurological systems. Transmitters and their receptors, including 5-hydroxytryptamine, dopamine, γ-aminobutyric acid, and histamine, play an important role in IBS, especially in visceral sensitivity and gastrointestinal motility. Studies in this field have shed light on revealing the mechanism by which neurotransmitters act in the pathogenesis of IBS and discovering new therapeutic strategies based on traditional pharmacological approaches that target the nervous system or novel therapies that target the microbiota.

The role of tyrosine hydroxylase-dopamine pathway in Parkinson's disease pathogenesis

BACKGROUND

Parkinson's disease (PD) is characterized by selective and progressive dopamine (DA) neuron loss in the substantia nigra and other brain regions, with the presence of Lewy body formation. Most PD cases are sporadic, whereas monogenic forms of PD have been linked to multiple genes, including Leucine kinase repeat 2 (LRRK2) and PTEN-induced kinase 1 (PINK1), two protein kinase genes involved in multiple signaling pathways. There is increasing evidence to suggest that endogenous DA and DA-dependent neurodegeneration have a pathophysiologic role in sporadic and familial PD.

METHODS

We generated patient-derived dopaminergic neurons and human midbrain-like organoids (hMLOs), transgenic (TG) mouse and Drosophila models, expressing both mutant and wild-type (WT) LRRK2 and PINK1. Using these models, we examined the effect of LRRK2 and PINK1 on tyrosine hydroxylase (TH)-DA pathway.

RESULTS

We demonstrated that PD-linked LRRK2 mutations were able to modulate TH-DA pathway, resulting in up-regulation of DA early in the disease which subsequently led to neurodegeneration. The LRRK2-induced DA toxicity and degeneration were abrogated by wild-type (WT) PINK1 (but not PINK1 mutations), and early treatment with a clinical-grade drug, α-methyl-L-tyrosine (α-MT), a TH inhibitor, was able to reverse the pathologies in human neurons and TG Drosophila models. We also identified opposing effects between LRRK2 and PINK1 on TH expression, suggesting that functional balance between these two genes may regulate the TH-DA pathway.

CONCLUSIONS

Our findings highlight the vital role of the TH-DA pathway in PD pathogenesis. LRRK2 and PINK1 have opposing effects on the TH-DA pathway, and its balance affects DA neuron survival. LRRK2 or PINK1 mutations can disrupt this balance, promoting DA neuron demise. Our findings provide support for potential clinical trials using TH-DA pathway inhibitors in early or prodromic PD.

Independent and Joint Associations of Tea Consumption and Smoking with Parkinson's Disease Risk in Chinese Adults

BACKGROUND

Existing limited evidence suggests that smoking and tea consumption may be associated with a lower risk of Parkinson's disease (PD). However, less is known about the independent and joint roles of these two habits, which are often clustered among Chinese, on PD risk.

OBJECTIVE

To prospectively examine the independent and joint association of tea consumption and smoking with the risk of PD.

METHODS

The China Kadoorie Biobank (CKB) study recruited 512,725 participants aged 30 to 79 years from ten areas across China since 2004. Information on smoking and tea consumption was collected at baseline, and PD cases were ascertained by linkage to the national health insurance system and death registry. Cox proportional hazards models were used to estimate the multivariable-adjusted hazard ratios (HRs) and corresponding 95%confidence intervals (CIs).

RESULTS

During a median of 10.8 years of follow-up, 922 PD cases were recorded. Compared with participants who never consumed tea, the HR (95%CI) for daily consumers was 0.68 (0.55, 0.84). Compared with participants who never or occasionally smoked, the HR (95%CI) for current smokers was 0.66 (0.53, 0.82). Those who had a clustering habit of smoking and tea consumption had a 38%(HR = 0.62; 95%CI: 0.49, 0.79) lower PD risk than those who consumed none. However, there were no statistically significant multiplicative or additive interaction for tea consumption and smoking on PD risk.

CONCLUSION

We found that smoking and daily tea consumption were independently inversely associated with the risk of PD.

Targeting Mitochondria by Plant Secondary Metabolites: A Promising Strategy in Combating Parkinson's Disease

Parkinson’s disease (PD) is one of the most prevalent and debilitating neurodegenerative conditions, and is currently on the rise. Several dysregulated pathways are behind the pathogenesis of PD; however, the critical targets remain unclear. Accordingly, there is an urgent need to reveal the key dysregulated pathways in PD. Prevailing reports have highlighted the importance of mitochondrial and cross-talked mediators in neurological disorders, genetic changes, and related complications of PD. Multiple pathophysiological mechanisms of PD, as well as the low efficacy and side effects of conventional neuroprotective therapies, drive the need for finding novel alternative agents. Recently, much attention has been paid to using plant secondary metabolites (e.g., flavonoids/phenolic compounds, alkaloids, and terpenoids) in the modulation of PD-associated manifestations by targeting mitochondria. In this line, plant secondary metabolites have shown promising potential for the simultaneous modulation of mitochondrial apoptosis and reactive oxygen species. This review aimed to address mitochondria and multiple dysregulated pathways in PD by plant-derived secondary metabolites.

Parkinson's Disease Dementia: Synergistic Effects of Alpha-Synuclein, Tau, Beta-Amyloid, and Iron

Parkinson’s disease dementia (PDD) is a common complication of Parkinson’s disease that seriously affects patients’ health and quality of life. At present, the process and pathological mechanisms of PDD remain controversial, which hinders the development of treatments. An increasing number of clinical studies have shown that alpha-synuclein (α-syn), tau, beta-amyloid (Aβ), and iron are closely associated with PDD severity. Thus, we inferred the vicious cycle that causes oxidative stress (OS), due to the synergistic effects of α-syn, tau, Aβ, and, iron, and which plays a pivotal role in the mechanism underlying PDD. First, iron-mediated reactive oxygen species (ROS) production can lead to neuronal protein accumulation (e.g., α-syn andAβ) and cytotoxicity. In addition, regulation of post-translational modification of α-syn by iron affects the aggregation or oligomer formation of α-syn. Iron promotes tau aggregation and neurofibrillary tangles (NFTs) formation. High levels of iron, α-syn, Aβ, tau, and NFTs can cause severe OS and neuroinflammation, which lead to cell death. Then, the increasing formation of α-syn, Aβ, and NFTs further increase iron levels, which promotes the spread of α-syn and Aβ in the central and peripheral nervous systems. Finally, iron-induced neurotoxicity promotes the activation of glycogen synthase kinase 3β (GSK3β) related pathways in the synaptic terminals, which in turn play an important role in the pathological synergistic effects of α-syn, tau and Aβ. Thus, as the central factor regulating this vicious cycle, GSK3β is a potential target for the prevention and treatment of PDD; this is worthy of future study.

NRF2 Activation and Downstream Effects: Focus on Parkinson's Disease and Brain Angiotensin

Reactive oxygen species (ROS) are signalling molecules used to regulate cellular metabolism and homeostasis. However, excessive ROS production causes oxidative stress, one of the main mechanisms associated with the origin and progression of neurodegenerative disorders such as Parkinson's disease. NRF2 (Nuclear Factor-Erythroid 2 Like 2) is a transcription factor that orchestrates the cellular response to oxidative stress. The regulation of NRF2 signalling has been shown to be a promising strategy to modulate the progression of the neurodegeneration associated to Parkinson's disease. The NRF2 pathway has been shown to be affected in patients with this disease, and activation of NRF2 has neuroprotective effects in preclinical models, demonstrating the therapeutic potential of this pathway. In this review, we highlight recent advances regarding the regulation of NRF2, including the effect of Angiotensin II as an endogenous signalling molecule able to regulate ROS production and oxidative stress in dopaminergic neurons. The genes regulated and the downstream effects of activation, with special focus on Kruppel Like Factor 9 (KLF9) transcription factor, provide clues about the mechanisms involved in the neurodegenerative process as well as future therapeutic approaches.

MZF1 alleviates oxidative stress and apoptosis induced by rotenone in SH-SY5Y cells by promoting RBM3 transcription

OBJECTIVE

To investigate the protective effect of MZF1/RBM3 on rotenone-induced neuronal injury.

METHODS

Rotenone (1 μM) was used to treat SH-SY5Y cells for 24 hr to simulate the cellular model of Parkinson's disease (PD), followed by detection of SH-SY5Y cell activities using MTT assay. MZF1 expression in rotenone-treated SH-SY5Y cells was detected by qRT-PCR and Western blot. MZF1 overexpression plasmid or MZF1 overexpression plasmid and RBM3 siRNA was transfected into SH-SY5Y cells, and then the expressions of MZF1 and RBM3 were detected. Oxidative stress (OS) in SH-SY5Y cells was detected using CMH2DCF-DA probes. Cell apoptosis rate was detected by flow cytometry. CHIP assay and dual-luciferase reporter assay were used to detect the binding between MZF1 and RBM3 promoter.

RESULTS

The expression of MZF1 was significantly lower in the rotenone-induced SH-SY5Y cells. Overexpression of MZF1 significantly reduced OS and apoptosis in rotenone-induced SH-SY5Y cells. MZF1 was a transcription factor of RBM3, which promoted the transcription of RBM3, and knockdown of RBM3 inhibited the protective effect of MZF1 overexpression on SH-SY5Y cells.

CONCLUSION

MZF1 alleviates OS and apoptosis induced by rotenone in SH-SY5Y cells by promoting RBM3 transcription.

Flavonoids modulate AMPK/PGC-1α and interconnected pathways toward potential neuroprotective activities

As progressive, chronic, incurable and common reasons for disability and death, neurodegenerative diseases (NDDs) are significant threats to human health. Besides, the increasing prevalence of neuronal gradual degeneration and death during NDDs has made them a global concern. Since yet, no effective treatment has been developed to combat multiple dysregulated pathways/mediators and related complications in NDDs. Therefore, there is an urgent need to create influential and multi-target factors to combat neuronal damages. Accordingly, the plant kingdom has drawn a bright future. Among natural entities, flavonoids are considered a rich source of drug discovery and development with potential biological and medicinal activities. Growing studies have reported multiple dysregulated pathways in NDDs, which among those mediator AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) play critical roles. In this line, critical role of flavonoids in the upregulation of AMPK/PGC-1α pathway seems to pave the road in the treatment of Alzheimer's disease (AD), Parkinson's disease (PD), aging, central nervous system (brain/spinal cord) damages, stroke, and other NDDs. In the present study, the regulatory role of flavonoids in managing various NDDs has been shown to pass through AMPK/PGC-1α signaling pathway.

Molecular mechanisms and applications of tea polyphenols: A narrative review

Tea is a worldwide popular drink with high nutritional and medicinal values as it is rich in nutrients, such as polyphenols, amino acids, vitamins, glycosides, and so on. Among them, tea polyphenols (TPs) are the current research hotspot. TPs are known to have multiple biological activities such as anti-oxidation, anti-tumor, anti-inflammation, anti-bacteria, lowering lipid, and liver protection. By reviewing a large number of literatures, we explained the mechanism of TPs exerting biological activity and a wide range of applications. We also discussed the deficiencies and development potential of TPs, in order to provide theoretical reference and scientific basis for the subsequent development and utilization of TPs. PRACTICAL APPLICATIONS: We summarized the bioactivity mechanisms of TPs in anti-tumor, anti-oxidation, antibacterial, anti-inflammatory, lipid-lowering, and liver protection, focused on its application fields in food and medicine, and discussed the deficiency and development potential of current research on TPs, so as to provide a certain convenient way for scholars studying TPs. It is expected to contribute to the subsequent discovery of biological activity and the broadening of the field of TPs.

Ferritinophagy-Mediated Ferroptosis Involved in Paraquat-Induced Neurotoxicity of Dopaminergic Neurons: Implication for Neurotoxicity in PD

Parkinson's disease (PD) is a progressive nervous system disorder. Until now, the molecular mechanism of its occurrence is not fully understood. Paraquat (PQ) was identified as a neurotoxicant and is linked to increased PD risk and PD-like neuropathology. Ferroptosis is recognized as a new form of regulated cell death. Here, we revealed a new underlying mechanism by which ferritinophagy-mediated ferroptosis is involved in PD induced by PQ. The effect of PQ on movement injury in mice was investigated by the bar fatigue and pole-climbing test. SH-SY5Y human neuroblastoma cells were used to evaluate the mechanism of ferroptosis. Our results showed that PQ induced movement injury by causing the decrease in tyrosine hydroxylase in mice. In vitro, PQ significantly caused the iron accumulation in cytoplasm and mitochondria through ferritinophagy pathway induced by NCOA4. Iron overload initiated lipid peroxidation through 12Lox, further inducing ferroptosis by producing lipid ROS. PQ downregulated SLC7A11 and GPX4 expression and upregulated Cox2 expression significantly, which were important markers in ferroptosis. Fer-1, an inhibitor of ferroptosis, could significantly ameliorate the ferroptosis induced by PQ. Meanwhile, Bcl2, Bax, and p-38 were involved in apoptosis induced by PQ. In conclusion, ferritinophagy-mediated ferroptosis pathway played an important role in PD occurrence. Bcl2/Bax and P-p38/p38 pathways mediated the cross-talk between ferroptosis and apoptosis induced by PQ. These data further demonstrated the complexity of PD occurrence. The inhibition of the ferroptosis and apoptosis together may be a new strategy for the prevention of neurotoxicity or PD in the future.

Nrf2 as a potential target for Parkinson's disease therapy

Parkinson's disease (PD) is a complex neurodegenerative disorder featuring both motor and nonmotor symptoms associated with a progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Conventionally, PD treatment options have focused on dopamine replacement and provide only symptomatic relief. However, disease-modifying therapies are still unavailable. Mechanistically, genetic and environmental factors can produce oxidative stress which has been implicated as a core contributor to the initiation and progression of PD through the degeneration of dopaminergic neurons. Importantly, nuclear factor erythroid 2-related factor 2 (Nrf2) is essential for maintaining redox homeostasis by binding to the antioxidant response element which exists in the promoter regions of most genes coding for antioxidant enzymes. Furthermore, protein kinase C, mitogen-activated protein kinases, and phosphotidylinositol 3-kinase have been implicated in the regulation of Nrf2 activity during PD. Here, we review the evidence supporting the regulation of Nrf2 through Keap1-dependent and Keap1-independent mechanisms. We also address that targeting Nrf2 may provide a therapeutic option to mitigate oxidative stress-associated PD. Finally, we discuss currently known classes of small molecule activators of Nrf2, including Nrf2-activating compounds in PD.

Effects of α-Synuclein-Associated Post-Translational Modifications in Parkinson's Disease

α-Synuclein (α-syn), a small highly conserved presynaptic protein containing 140 amino acids, is thought to be the main pathological hallmark in related neurodegenerative disorders. Although the normal function of α-syn is closely involved in the regulation of vesicular neurotransmission in these diseases, the underlying mechanisms of post-translational modifications (PTMs) of α-syn in the pathogenesis of Parkinson's disease (PD) have not been fully characterized. The pathological accumulation of misfolded α-syn has a critical role in PD pathogenesis. Recent studies of factors contributing to α-syn-associated aggregation and misfolding have expanded our understanding of the PD disease process. In this Review, we summarize the structure and physiological function of α-syn, and we further highlight the major PTMs (namely phosphorylation, ubiquitination, nitration, acetylation, truncation, SUMOylation, and O-GlcNAcylation) of α-syn and the effects of these modifications on α-syn aggregation, which may elucidate mechanisms for PD pathogenesis and lay a theoretical foundation for clinical treatment of PD.